Solar Cell efficiency is low, and would likely be ineffective given the limited sun-exposed faces of the aircraft. Using a quantum-dot paint for solar could be viable (they're far more efficient). Secondly, batteries are currently very heavy, which would be a problem. Lightweight, structural batteries would help greatly with that issue. Thirdly, batteries don't really store enough energy currently. Next-generation structural batteries potentially could, but those are some years off. Lastly, the anodes and cathodes of current batteries degrade too quickly. There are upcoming technolgies that can withstand tens of thousands of recharge cycles, but they're all very preliminary. Since planes are expected to have very long life spans, that makes electrical planes currently impractical. Given the above technologies, electrical planes will be very practical within probably 20-30 years. Until then, they are impractical because, logistically speaking, you charge up the plane and, while it's flying, let the solar do all it can to keep the batteries up. The distance the plane can travel, then, is a function of its total stored energy and all of the energy collected from the solar.

Assuming you're not worried about backup speed, you could use a four-bay external hard-drive enclosure in combination with RSYNC and LVM on any linux variety. I don't know if they all do, but the MediaSonic HF2-SU3S2 supports 3TB hard drives per bay, which means that two of them could be used in conjunction to provide 24TB of backup storage. Since you can make a large volume out of the full 24TB using LVM, you could even use something like dd to write to the disk (RSYNC with the archive option would be a better choice though, imho).

The issue with this argument is that they aren't rebroadcasting, they're just directing the signal as a slingbox would. There is exactly one end user unit (could be a person or a household) of the information, and it is not being made publicly available. If I set up a slingbox in my livingroom, it is legal to use that slingbox to consume the signal on another of my devices. What if I set up a slingbox on a roof in Brooklyn and streamed the content to my house in Texas? The only difference between these scenarios is geography. What I see here is the case of a company saying, "Instead of having you own the antenna in Brooklyn, we'll set up the antenna and the tunnel for you, and you can consume it how you wish."

Adversely affect the actual output? Sure. The problem isn't the effectiveness of the output, though, it's the output itself. This may sound ridiculous, but we get enough sunlight that most parts of Earth could positively contribute, especially if much of that land is not biome-valuable. In the cases of Alaska, Texas and the Mojave, we have incredible potential for output, with little-to-no biome detriment.